Despite that rocky start, Callaghan is warm and engaging as we discuss her move from the UK to the United States and her idea for carrying out smaller gigs, known as house concerts. Callaghan's break came when she decided to write to Mullins about working together.
"Initially I thought I'd go to the States and give it a year and see how it goes. And that turned into two or three years and now five years has gone by. I've been lucky to build my audience to establish myself and headline my own shows. Three years ago I moved to Nashville, where I am based now."
But the Nashville residency is a little misleading. Although Callaghan has been backed by the likes of Bob Harris and appeared at the Country 2 Country festival, her music is not really country. There is a Celtic tinge to her folky pop, which has a smiley sheen, where no problem in the world seems too big to deal with. This uplifting music matches her personality. With a broad smile and genuine delight, she shares her experiences from the US and looks back at how it all started.
"My Space kinda kicked off the whole journey, it was how I got in touch with Shawn Mullins. The internet has helped me grow my audience. I play a mixture of shows, standard public gigs but since I have been living in the States I have been introduced to the idea of the house show. This used to be something I did in between my regular shows. I thought if I had an evening free I might as well do something. So someone invites 30 to 40 friends to their house for a show - depending on the size of the house of course - and it's a great way to make a strong connection with people. They go home and hopefully tell their friends about it and the word spreads. In 2013, Steve (her husband and manager) decided to do a trip across America, performing house shows all the way. It was a month long, about 25 shows. It was crazy but great fun."
That trip across the States started in Boston, apt considering that was where she first lived in the UK. She's used to moving though as her father was in the RAF, so Callaghan spent quite a lot of her life in different places. Perhaps that explains why she did another house show tour across America soon after the first. This year she did an 'All Four Corners' tour, with 36 of these shows around the US. Now she's decided to bring the idea to the UK.
"The concept isn't a familiar one in the UK and I told friends in the States that land is more expensive here so the size of property will be smaller. But the first one I turned up at was like a stately home! It's gone well and something I will do again. For a performer I think it's a good thing to do. For some artists the idea of house concert fills them with absolute dread, you do have to be one of those artists that feels comfortable in that intimate environment."
Confidence doesn't ever seem to have been a problem for Callaghan - or at least the thought of going for it, having nothing to lose. Hence that Shawn Colvin, sorry Shawn Mullins connection!
"I was of the idea that 'what's the worst that can happen?'. I f he didn't reply that wasn't the end of the world. I just thought I'd drop him a message and see what happens. Luckily I had been mentioned by a colleague to him and so he was already aware of my name. I moved to the States to work with him and it was an amazing experience. Shawn will always be someone I can turn to for advice as he's been through it. From being an independent artist to someone selling loads of records. He's busy doing a new record right now but I always keep in touch."
Callaghan admits that since she moved away she has missed the UK a touch. Her recent tour will be followed by more shows later this autumn. I expect we are soon to see plenty more of this talented singer.